The present invention relates generally to a sub-oceanic or underwater cable network system and method, and is particularly concerned with a method and apparatus for improved initial deployment and subsequent expansion or revision of such undersea network systems.
In current methods used for sub-oceanic cable deployment and maintenance, all activities relating to the deployment, development, expansion or modification of electrical and/or fiber optic cables require the use of ship-board installation and maintenance facilities. This is true whether the cable is in the process of initial deployment, or when a previously deployed cable is to be repaired, re-connected, or re-directed. The joining or branching of such cables is carried out by means of splices, using any of several well known splicing techniques. However, splicing is time consuming, labor intensive, and is of a permanent, one-time only nature. This imposes a burden of added labor when such splicing has to be revised or rejoined.
In addition, once a cable has been joined, either by a separable connector or a permanent splice, and deposited on the sea floor, any revision to the junction requires retrieval of the cable from its resting place on the sea floor, to allow any necessary maintenance or alterations to be made at a ship-board maintenance facility. The retrieval of such cables after they have previously been deposited on the sea floor is a physically and technically demanding operation, making cable network modifications very expensive and time consuming. These difficulties increase when cables have been deposited into greater depths of sea water, or into sea floor environments of complex topography. Additionally, the actual expense of such operations, as well as the physical hazards related thereto, are highly vulnerable to the adversities of weather, sea currents, and other natural phenomena. The time required to complete cable retrieval, maintenance, and re-deployment is always a significant factor in the cost of sub-oceanic cable network operations. This factor becomes critical when such procedures have to be conducted for the purpose of reinstating service which has become interrupted by an inadvertent circuit failure. There has therefore long been a need for a more rapid, efficient and cost-effective method of servicing and modifying sub-oceanic cable networks.
Another problem in sub-oceanic cable installations occurs at locations where a plurality of remotely deployed cables are terminated to a single, on-shore node. Each xe2x80x9con-shore to off-shorexe2x80x9d cable run must be validated by an independent government permit. Thus, each time capacity is increased, requiring a new on-shore to off-shore cable run, a new permit must be obtained.
It is an object of the present invention to provide a new and improved sub-oceanic or underwater cable system and method, as well as a new and improved junction box for use in such a system.
According to one aspect of the present invention, an underwater junction box for installation on the ocean floor to form part of a sub-oceanic cable network is provided, which comprises an outer pressure housing having a plurality of ports, at least some of the ports comprising a first part of a wet mateable underwater connector for releasable sealing connection with second part of the underwater connector provided at the end of a sub-sea cable, and a circuit routing unit in the housing connecting each first connector part in a respective port to a respective different port of housing.
Two different types of junction box may be provided, with a first junction box comprising an on-shore to off-shore junction box for use at an off-shore location installed at a predetermined distance off-shore from an on-shore cable junction node, and a second junction box comprising an off-shore junction box for routing of transoceanic cables. The first junction box has an input for connection to an end of a single on-shore to off-shore conduit having a high circuit count, as well as a plurality of ports each designed for selective connection to a single offshore cable, and the circuit routing unit connects each port to the input whereby each port is connected to respective circuits in the single onshore to off-shore conduit. The second junction box has a plurality of ports for connection to transoceanic cables and the circuit routing unit connects each port to another transoceanic cable port, whereby a desired number of incoming cables can be connected to a desired corresponding number of outgoing cables at a junction in a transoceanic cable network.
According to another aspect of the present invention, a cable system for installation on the ocean floor or under another body of water is provided, which comprises a plurality of sub-sea junction boxes installed at spaced locations throughout a predetermined sub-oceanic cable network, the junction boxes including at least some off-shore junction boxes each installed at a predetermined distance off-shore from a respective on-shore cable junction node, a main off-shore to on-shore conduit having a high circuit count extending from each off-shore junction box to the respective on-shore cable junction node, each off-shore junction box comprising an outer housing having plurality of ports for connection to a respective cable, and circuit routing within the housing connecting at least some of the ports to circuits in the off-shore to on-shore conduit.
In a typical initial installation, the circuits will comprise optical fibers or optical fibers and electrical wires. Initially, only some of the ports will be connected to cables in the sub-oceanic network, leaving some unused paths from unconnected ports through the junction box to currently unused fibers in the off-shore to on-shore conduit. This allows for subsequent expansion of the network without requiring additional permits for new off-shore to on-shore cables, as well as potential parallel or redundant circuit paths for added system reliability. The fiber routing in the housing may also connect some of the ports to other ports on the junction box, for connection of one incoming cable to another cable running offshore, rather than to the on-shore node. Additionally, the fiber routing assembly may include suitable switches for re-routing electrical wires and optical fibers between input ports and other outlets such as the off-shore to on-shore conduit or other ports on the junction box, as well as amplification and wavelength distribution devices if required.
The ports on the junction box each comprise one half of a wet mateable, plug and socket-like electro-optic or fiber optic underwater connector, with the other half of the connector being provided at the end of the cable to be connected to the port. Any suitable wet-mateable underwater connector may be used to implement this system, such as the rolling seal underwater connectors described in U.S. Pat. Nos. 5,738,535 or 6,017,227 of Cairns, the connector described in pending application Ser. No. 09/641,313 of Barlow et al., filed Aug. 18, 2000, or the connectors described in co-pending application Ser. No. 09/418,145 of Cairns, filed Oct. 14, 1999, or application Ser. No. 09/761,917 of Cairns et al., filed Jan. 17, 2001, the contents of each of which are incorporated herein by reference. Thus, these ports will be automatically sealed shut when not connected to any cable, and can be readily connected to a cable and subsequently disconnected, if desired, by a remotely operated, remote oceanic vehicle or ROV. The large fiber/electrical wire conduit running from the on-shore node to the junction box can be permanently or removably plumbed into the junction box.
This arrangement provides for quick and inexpensive off-shore circuit expansion as needed for increased system capacity, as well as the added security of redundant channels, and the ability for system upgrade without requiring additional environmental permits to run cables on-shore.
According to another aspect of the present invention, a sub-oceanic cable network installation method is provided, which comprises the steps of:
installing a plurality of junction boxes at predetermined subsea locations throughout a sub-oceanic cable network, including at least some off-shore junction boxes each located at a predetermined off-shore location at a predetermined distance from a respective on-shore cable network node, each junction box having a plurality of cable inlet/outlet ports;
running a high circuit count conduit from each on-shore cable node to the respective off-shore junction box for that node, and connecting the circuits in the conduit to a cable routing assembly in the box; and
connecting at least some of the cable inlet/outlet ports to offshore cables in the network to provide a path from at least some of the connected offshore cables through the cable routing assembly to the onshore node via circuits in the conduit.
At a later date, if the network capacity is to be increased, additional offshore cables are connected to as yet unused ports on at least some of the off-shore junction boxes for connection to previously unused circuit paths in the conduit. The cable routing assembly may connect some of the junction box ports to other junction box ports, such that one offshore cable running along a coast-line, for example, may be connected to another offshore cable running from the junction box to another junction box in the network.
The system and method of this invention avoids the need to obtain additional permits to run cables on-shore each time a network capacity is increased. Instead, a single, high capacity conduit carrying much more electrical and fiber optic circuit links than a typical single underwater cable is run from an on shore node to the off-shore junction box, so that at least some of the circuit links are initially unused and can be added in as needed. The conduit may carry ten or more times the number of circuits provided in a typical underwater telecommunications cable. The system also avoids the need to make the cable connections at an on-board cable maintenance station, by using readily connectable and disconnectable underwater connectors which can be manipulated by an ROV. This also avoids the need for permanent cable splicing, and makes reconfiguration of the circuits much easier to implement.